Cellular communications networks have evolved over time such that there are now a variety of network technologies available in the marketplace. As technology advances, newer systems are deployed. However, older legacy systems cannot be made immediately obsolete. Older legacy systems require maintenance for a variety of reasons. For example, the cost of upgrading equipment may be prohibitive. As well, an installed customer base may rely on installed equipment and resist expenditures for newer technology.
Two such presently deployed network technologies are second generation (2G) cellular systems and third generation (3G) cellular systems. 3G networks are the newer generation of the two and provide many existing 2G services as well as adding additional services. Examples of 2G networks include interim standard-41 (IS-41) and global system for mobile communications (GSM) networks. Examples of 3G networks include session initiation protocol (SIP)-based networks, Internet protocol (IP) multimedia subsystem (IMS) networks and cellular internet access networks.
One service that is available in both systems is short message service (SMS). Short message service (SMS), which was first introduced by European wireless network operators in 1991, enables mobile subscribers to easily send and receive text messages via wireless handsets. Although specifications and industry standards related to SMS are constantly evolving and being modified, SMS messages have traditionally been used to convey readable text information, where the text may include any combination of characters that may be entered via a keypad or keyboard. Multimedia message service (MMS) extends the basic SMS concept to include a variety of message content types, including text, still images, video, and audio.
SMS delivery service provides a mechanism for transmitting messages to and from SMS capable terminals (e.g., wireless handsets, personal computers, etc.) via a signaling component of the wireless communication network. With particular regard to the sending and receiving of SMS messages by a wireless handset, a signaling network provides the transport facilities necessary to communicate short messages between a store-and-forward network element, known as a short message service center (SMSC), and a wireless handset.
In contrast to earlier text message transmission services, such as alphanumeric paging, SMS technology is designed to provide guaranteed delivery of an SMS message to a destination. That is, if a temporary network failure or the unavailability of a message recipient prohibits the immediate delivery of an SMS message, then the SMS message is stored in the network (i.e., at an SMSC) until the destination/intended message recipient becomes available. Another of the key and distinguishing characteristics of SMS service, with respect to previously available message communication services, is that an active mobile handset is able to send or receive a short message at any time, regardless of whether or not a voice or data call is in progress.
Internet engineering task force (IETF) request for comments number 2916 (RFC 2916) describes an ENUM system for facilitating the interconnection of communications networks that rely on telephone numbers with the communications networks that utilize the domain name system (DNS). In particular, the ENUM system can map a particular number referred to as an E.164 number to one or more uniform resource identifiers (URIs) in the DNS. URIs are strings of characters that identify resources, such as documents, images, files, databases, e-mail addresses, websites or other resources or services in a common structured format. A URI can include among other things a SIP URI, an instant messaging (IM) identifier, an e-mail address identifier, an Internet chat session identifier, and an IP address.
To assist with the routing of SMS messages in a 3G network, the ENUM system may be used to find a delivery address of an SMS message recipient. However, improper provisioning of the ENUM database or the absence of a 3G delivery address for the SMS message may result in the SMS message being undeliverable even when the intended message recipient is reachable via a 2G network address. Accordingly, there exists a need for improved methods, systems, and computer program products for using an E.164 number (ENUM) database for message service message routing resolution among 2G and 3G network systems.